He was the rival of Scaliger in the science of chronology; his doctrinal works are praised as 'a monument of useful labour'; 'he solaced his leisure hours with Greek and Hebrew, as well as Latin verse,' and, according to Hallam's judgment, obtained in the last subject the general approbation of the critics.
His library contained several books that had belonged to Grolier; but it was chiefly remarkable for its mss., of which several were published by Sirmond and Du Chesne among other materials for the history of France.
Many of them had been acquired from the collection of Greek and Hebrew books formed by Jean de Saint André, or out of the mass of chronicles, romances, and old French poems belonging to Claude Fauchet, and a large portion came, as we have seen, out of an ancient Benedictine Abbey.
The printed books, comprising a number of finely illustrated works on archæology, were sold at the Hague in 1722; the sale included the old library inherited by Francis Mansard, and the mss.
A thousand splendid volumes on parchment, the pride of the elder Pétau, described by all who saw them in terms of glowing admiration, were sold in his son's lifetime to Queen Christina of Sweden.